Multi-protocol label switching (MPLS) has heretofore been discussed, in which an identifier called a label is added to the beginning of each packet for transfer to achieve an increase in the communication speed and/or addition of functions. In the MPLS, a path called a Label Switched Path (LSP) is used to transfer packets.
A technology to classify packets and perform transfer control to the packets in accordance with the priorities based on the classes is proposed in order to provide Quality of Service (QoS) in communication systems. In the provision of the QoS in the MPLS, Label-only-inferred per hop behavior (PHB) scheduling class (PSC) LSP (L-LSP) or EXP-inferred PSC LSP (E-LSP) is used (for example, refer to Japanese Laid-open Patent Publication No. 2002-44139).
In the L-LSP, one LSP has one class and traffics are allocated to multiple LSPs having different classes. Accordingly, the label of each packet indicates the priority in the L-LSP. In the E-LSP, a Traffic Class (TC) value for identifying each class is written into a TC field (Exp field) of each label. Accordingly, the TC value of each packet indicates the priority in the E-LSP.
Since the method of identifying the priority in the E-LSP is different from that in the L-LSP, as described above, a communication apparatus performing the transfer control determines whether a packet that is a target for the transfer control is transferred on the E-LSP or the L-LSP. The communication apparatus allocates the priorities by using an E-LSP process and an E-LSP table for the packets on the E-LSP, and allocates the priorities by using an L-LSP process and an L-LSP table for the packets on the L-LSP.